package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import lombok.extern.slf4j.Slf4j;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 * 服务实现类
 * </p>
 *
 * @author 虎哥
 * @since 2021-12-22
 */
@Service
@Slf4j
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {

    @Autowired
    private ISeckillVoucherService seckillVoucherService;
    @Autowired
    private RedisIdWorker redisIdWorker;
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
    @Autowired
    private RedissonClient redissonClient;

    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;

    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }

    /**
     * 阻塞队列
     */
//    private final BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024 * 1024);

    /**
     * 线程池, 只有一个单线程
     */
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();

    // 在类初始化之后执行，因为当这个类初始化好了之后，随时都是有可能要执行的
    @PostConstruct
    private void init() {
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandler());
    }

    private class VoucherOrderHandler implements Runnable {

        String queueName = "stream.orders";

        @Override
        public void run() {
            while (true) {
                try {
                    // 1. 获取消息队列中的订单信息 xreadgroup group g1 c1 count 1 block 2000 streams stream.orders >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    // 2. 判断消息获取是否成功
                    if (list == null || list.isEmpty()) {
                        // 2.1. 如果获取失败, 说明没有消息, 继续下一次循环
                        continue;
                    }
                    // 3. 解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 4. 如果获取成功, 可以下单
                    handleVoucherOrder(voucherOrder);
                    // 5. ack确认 sack stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    handlePendingList();
                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    // 1. 获取pending-list中的订单信息 xreadgroup group g1 c1 count 1 block 2000 streams stream.orders >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    // 2. 判断消息获取是否成功
                    if (list == null || list.isEmpty()) {
                        // 2.1. 如果获取失败, 说明pending-list没有异常消息, 结束循环
                        break;
                    }
                    // 3. 解析消息中的订单信息
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> value = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(value, new VoucherOrder(), true);
                    // 4. 如果获取成功, 可以下单
                    handleVoucherOrder(voucherOrder);
                    // 5. ack确认 sack stream.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());

                } catch (Exception e) {
                    log.error("处理pending-list订单异常", e);
                    try {
                        Thread.sleep(20);
                    } catch (InterruptedException ex) {
                        throw new RuntimeException(ex);
                    }
                }
            }
        }
    }

/*    private class VoucherOrderHandler implements Runnable {

        @Override
        public void run() {
            while (true) {
                try {
                    // 1. 获取阻塞队列中的订单信息
                    VoucherOrder voucherOrder = orderTasks.take();
                    // 2. 创建订单
                    handleVoucherOrder(voucherOrder);
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                }
            }
        }
    }*/

    private void handleVoucherOrder(VoucherOrder voucherOrder) {
        proxy.createVoucherOrderAsync(voucherOrder);
    }

    private IVoucherOrderService proxy;

    @Override
    public Result secKillVoucher(Long voucherId) {
        // 1. 获取订单id
        Long orderId = redisIdWorker.nextId("order");

        // 2. 执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT, Collections.emptyList(),
                voucherId.toString(),
                UserHolder.getUser().getId().toString(),
                orderId.toString()
        );

        // 3. 判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            // 2.1. 不为0, 代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }

        // 4. 获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        // 5. 返回订单id
        return Result.ok(orderId);
    }


/*
    @Override
    public Result secKillVoucher(Long voucherId) {
        // 1. 执行lua脚本
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT, Collections.emptyList(),
                voucherId.toString(),
                UserHolder.getUser().getId().toString()
        );

        // 2. 判断结果是否为0
        int r = result.intValue();
        if (r != 0) {
            // 2.1. 不为0, 代表没有购买资格
            return Result.fail(r == 1 ? "库存不足" : "不能重复下单");
        }
        // 2.2. 为0, 有购买资格, 把下单信息保存到阻塞队列
        long orderId = redisIdWorker.nextId("order");
        // 2.3. 创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        voucherOrder.setId(orderId);
        // 2.4. 用户id
        voucherOrder.setUserId(UserHolder.getUser().getId());
        // 2.5. 代金券id
        voucherOrder.setVoucherId(voucherId);
        // 2.6. 放入阻塞队列
        orderTasks.add(voucherOrder);

        // 3. 获取代理对象
        proxy = (IVoucherOrderService) AopContext.currentProxy();

        // 4. 返回订单id
        return Result.ok(orderId);
    }
*/

/*    @Override
    public Result secKillVoucher(Long voucherId) {
        // 1. 查询优惠券
        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
        // 2. 判断秒杀是否开始
        if (voucher.getBeginTime().isAfter(LocalDateTime.now())) {
            // 尚未开始
            return Result.fail("秒杀尚未开始!");
        }
        // 3. 判断秒杀是否已经结束
        if (voucher.getEndTime().isBefore(LocalDateTime.now())) {
            // 已经结束
            return Result.fail("秒杀已经结束!");
        }
        // 4. 判断库存是否充足
        Integer stock = voucher.getStock();
        if (stock < 1) {
            // 库存不足
            return Result.fail("库存不足!");
        }
        Long userId = UserHolder.getUser().getId();
        // 创建锁对象
//        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
        RLock lock = redissonClient.getLock("lock:order:" + userId);
        // 获取锁对象, 无参相当于传参(-1, -1, TimeUnit.SECONDS), -1表示不等待, 失败了立即返回, 第二个-1表示使用默认的看门狗过期时间超过30秒自动释放
        boolean isLock = lock.tryLock();
        // 判断是否获取锁成功
        if (!isLock) {
            // 获取锁失败, 返回错误或重试
            return Result.fail("不允许重复下单");
        }
        try {
            IVoucherOrderService proxy = (IVoucherOrderService) AopContext.currentProxy();
            return proxy.createVoucherOrder(voucherId);
        } catch (IllegalStateException e) {
            throw new RuntimeException(e);
        } finally {
            lock.unlock();
        }
    }*/

    @Transactional
    public Result createVoucherOrder(Long voucherId) {
        // 5. 一人一单
        Long userId = UserHolder.getUser().getId();
        // 5.1. 查询订单
        Integer count = query().eq("user_id", userId).eq("voucher_id", voucherId).count();
        // 5.2. 判断是否存在
        if (count > 0) {
            // 用户已经购买过了
            return Result.fail("用户已经购买过一次!");
        }
/*        try {
            for (int i = 0; i < 20; i++) {
                // 模拟阻塞
                log.info("等待中...");
                Thread.sleep(1000);
            }
        } catch (InterruptedException e) {
            throw new RuntimeException(e);
        }*/
        // 6. 扣减库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherId)
                .gt("stock", 0)
                .update();
        if (!success) {
            // 库存不足
            return Result.fail("库存不足!");
        }
        // 7. 创建订单
        VoucherOrder voucherOrder = new VoucherOrder();
        // 7.1. 订单id
        Long orderId = redisIdWorker.nextId("order");
        voucherOrder.setId(orderId);
        // 7.2. 用户id
        voucherOrder.setUserId(UserHolder.getUser().getId());
        // 7.3. 代金券id
        voucherOrder.setVoucherId(voucherId);
        save(voucherOrder);
        // 8. 返回订单id
        return Result.ok(orderId);
    }

    @Transactional
    public void createVoucherOrderAsync(VoucherOrder voucherOrder) {
        // 1. 修改库存
        boolean success = seckillVoucherService.update()
                .setSql("stock = stock - 1")
                .eq("voucher_id", voucherOrder.getVoucherId())
                .gt("stock", 0)
                .update();
        if (!success) {
            // 库存不足
            log.error("库存不足!");
        }
        // 2. 创建订单
        save(voucherOrder);
    }
}